This invention is concerned with a new member of the acidic polycyclic ether group of antibiotics, a class of compounds characterized biologically by their effect on cation transport in mitochondria. This family of antibiotics includes monensin [J. Amer. Chem. Soc., 89-5737, (1967)]; nigericin [Biochem. Biophys. Res. Comm., 33:29, (1968)]; grisorixin [J. Chem.Soc.,Chem. Commun., 1421, (1970)]; dianemycin [J. Antibiotics 22:161, (1969)]; salinomycin [J. Antibiotics, 27:814, (1974)]; X-537A [J.Chem.Soc., Chem. Commun., 967, (1972)]; X-206 [J.Chem.Soc.Chem.Commun., 927, (1971)]; A204A [J.Amer.Chem.Soc., 95:3399,(1973)]; mutalomycin [J. Antibiotics, 30:903, (1977)]; ionomycin [J. Amer.Chem.Soc., 101:3344, (1979)]; K-41B [J. Antibiotics, 32:169, (1979)]; A-130B and A-130C [J. Antibiotics, 33:94, (1980)]; leuseramycin [ J. Antibiotics, 33:137, (1980)]; and A-28695 B [J. Antibiotics, 33:252, (1980)]. Also, the subject has been reviewed by Westley, "Polyether Antibiotics," Adv. Appl. Microbiol., 22:177 (1977).
The polycyclic ether antibiotics listed above are active against Gram-positive bacteria, fungi and protozoa. These antibiotics exhibit potent anticoccidial activity.
The well-known protozoan disease, coccidiosis, continues to be a serious problem and its control is of economic importance to veterinary science, especially to the poultry industry. Coccidiosis results from infection by one or more species of Eimeria or Isospora (for a summary, see Lund and Farr in "Disease of Poultry," 5th ed, Biester and Schwarte, Eds., Iowa State University Press, Ames, Ia., 1965, pp. 1056-1096). There are six species of coccidia which produce easily discernible morbidity in susceptible chickens. Eimeria tenella, E. necatrix. E. brunetti. E. acervulina, E. maxima and E. mivati produce damage either directly through destruction of epithelial cells of the digestive tract or indirectly through production of toxins. Three other species of protozoa belonging to the same genus are considered to be relatively innocuous; however, E. mitis, E. hagani and E. praecox are capable of reducing weight gain, lowering feed efficiency and adversely affecting egg production.
In view of the greater economic losses due to coccidiosis and the disadvantages of some known anticoccidial agents, the search for better anticoccidial agents continues.
Enteritis is another disease which can cause severe economic losses to livestock producers. Enteritis occurs in chickens, swine, cattle and sheep and is attributed mainly to anaerobic bacteria, particularly Clostridium perfringens, and viruses. Enterotoxemia in ruminants, an example of which is "overeating disease" in sheep, is a condition caused by C. perfringens infection.
Swine dysentery is one of the most common swine diseases diagnosed in the United States. Additionally, the disease is prevalent in many other countries and annually causes many thousands of dollars losses in stock to swine growers around the world. It has recently been discovered that a large spirochete is the causative organism of the disease. This organism, Treponema hyodysenteriae, has now been isolated and shown to be capable of producing the disease [Harris, D. L. et al.: "Swine Dysentery-1 Inoculation of Pigs with Treponema hyodysenteriae (New Species) and Reproduction of the Disease," Vet. Med/SAC,67: 61-64: 1972]. The test data recited hereinafter concerns tests conducted with this organism. It must be noted that it is not known whether T. hyodysenteriae is the sole causative organism of swine dysentery. From the data available, however, it can be concluded that it is a primary source of the infection.
Performance enhancement (increased rate of growth and/or increased efficiency of feed utilization) in ruminants, such as cattle, is another economically desirable objective of veterinary science. Of particular interest is growth promotion achieved by increasing feed-utilization efficiency. The mechanism for utilization of the major nutritive portion (carbohydrates) of ruminant feeds is well known. Microorganisms in the rumen of the animal degrade carbohydrates to produce monosaccharides and then convert these monosaccharides to pyruvate compounds. Pyruvates are metabolized by microbiological processes to form acetates, butyrates or propionates, collectively known as volatile fatty acids (VFA). For a more detailed discussion, see Leng in "Physiology of Digestion and Metabolism in the Ruminant," Phillipson et al., Eds., Oriel Press, Newcastle-upon-Tyne, England, 1970, pp 408-410.
The relative efficiency of VFA utilization is discussed by McCullough in "Feedstuffs," June 19, 1971, page 19; Eskeland et al. in J. An. Sci. 33, 282 (1971); and Church et al. in "Digestive Physiology and Nutrition of Ruminants," Vol. 2 1971, pp. 622 and 625. Although acetates and butyrates are utilized, propionates are utilized with greater efficiency. Furthermore, when too little propionate is available, animals may develop ketosis. A beneficial compound, therefore, stimulates animals to produce a higher proportion of propionates from carbohydrates, thereby increasing carbohydrate utilization efficiency and also reducing the incidence of ketosis.
Yet another disease which causes economic losses to livestock producers is caused by the protozoan parasite of the genus Theileria. That disease, theileriosis, is also known as "East Coast Fever," "Coaster fever" or "Rhodesian tick fever." The Theileria parasite invades but does not destroy red blood cells which gives rise to acute or chronic febrile infections. In cattle the disease is characterized by high fever, swelling of the lymph nodes, emaciation and high mortality. The disease is a very serious problem in East and Central Africa. For a more detailed discussion of theileriosis, see "The Merck Veterinary Manual," Siegmund et al., Eds., Merck & Co., Rahway, N.J., 5th Ed., pp. 431-433 (1979).